ABSTRACT Neonatal encephalopathy (NE) resulting from birth asphyxia constitutes a major global public health burden for millions of infants every year, and despite therapeutic hypothermia, half of neonates have poor neurologic outcomes. As new neuroprotective interventions are being studied in clinical trials, there is a critical need to establish physiological surrogate markers of therapeutic efficacy, to guide patient selection and/or to modify the therapeutic intervention. The challenge in the field of neonatal brain injury has been the difficulty to clinically discern the NE severity within the short therapeutic window after birth, or to analyze the dynamic aspects of the cerebral circulation in the NE sick newborns. The PI and her bioengineering team have developed a ?wavelet neurovascular bundle? analytical system that can measure cerebral autoregulation (CA) and neurovascular coupling (NVC) at multiple time scales under dynamic, non-stationary clinical conditions. A real time evaluation of the coupling of cerebral blood flow and neuronal activity ?neurovascular bundle? is therefore proposed in order to determine the severity of injury and identify infants that could potentially benefit from added therapies. The proposed approach not only has the ability to capture the evolving non-stationary aspects of the cerebral circulation, but can also quantify the magnitude and duration of the impaired hemodynamics in NE, and their effect on functional and structural outcomes. The PI has published her methodological technology development, together with preliminary observations linking the wavelet bundle measures to short- and long- term developmental outcomes following hypothermia. The long-term goal is to harness the technological advantages of the wavelet neurovascular bundle to optimize outcomes in asphyxiated newborns, by appropriately selecting patients for therapeutic trials and identifying the factors underlying responses to therapy. Erythropoietin (EPO), with postulated effects on cerebral blood flow, neurogenesis and angiogenesis, is currently being evaluated as a new adjunct therapy for moderate to severe NE (High dose EPO Asphyxia; NS092764 NCT02811263 NINDS1U01). The central hypothesis in this ancillary study at UT Southwestern is that the new wavelet neurovascular bundle measures will stratify the NE severity(Aim 1), identify the effects of EPO on CA/NVC during a new randomized neuroprotection trial of EPO + Hypothermia vs. Hypothermia alone (Aim 2), and predict short-term structural and long-term functional outcomes(Aim 3). To test this hypothesis, 100 newborns will be enrolled at UT Southwestern (30 non-treated mild NE and 70 moderate or severe NE who are randomized to treatment with EPO + Hypothermia or Hypothermia alone) and examined for developmental outcomes at 24months. New knowledge gained from the wavelet bundle will specifically provide:1) improved stratification of brain injury severity among newborns with NE, 2) understanding the effect of EPO on cerebral autoregulation and neuronal coupling, and 3) new bio-mediators that can predict responses to therapies in real time, aiming to improve brain outcomes as per NINDS mission.